As a rule of a thumb, can I say that when running an unsteady simulation in any turbulence model, when I achieve a periodic oscillation in my residuals and in mass-weighted average plots, etc. solution has converged?

If not, this means that mass-weighted average quantities must flatten like in steady simulations?

Then If I've understood well, when I am in unsteady problems I will get the convergence when my parameters of the flow (mass-weighted average and/or drag-coeff, etc.) have a (little) periodic oscillation, doesn't it?